Plague outbreak: How ancient teeth help scientist decode deadly disease took place 5,500 years ago

Ancient teeth from Siberia has helped researchers rewrite the plague’s timeline. Scientists have found the oldest known evidence of the plague, which sparked deadly outbreaks dating back about 5,500 years ago — some 200 years earlier than previously thought. The disease has sickened humans for thousands of years and wiped out a significant chunk of Europe's population in the 14th century during what's known as the Black Death. Though rare, the plague is still around today and is treated with antibiotics.

About 5,500 years ago, bands of hunter-gatherers inhabited the Lake Baikal region in Siberia, sustained by rich resources including prey such as elk, deer, moose, fish, seals and rodents called marmots. These people became victims of the earliest-known plague outbreak, especially children and adolescents.

Plague in Siberia


Researchers said ancient DNA obtained from bodies interred in four burial sites in the area revealed the presence of the oldest-known strains of Yersinia pestis, the plague bacterium. These prehistoric deaths presaged the immense suffering that this pathogen has visited on humankind over the millennia.

The researchers said the outbreak was particularly deadly for the young, judging ‌from the burial sites, and ⁠attributed this to ⁠genetic traits in these strains that no longer are present in today's iteration of the pathogen. They also said the discovery adds to evidence that marmots were the bacterium's original host species, and that plague arose in central or northeastern ​Asia before spreading across Eurasia.

“To understand our own history, we believe that understanding the history of plague is extremely important,” said study co-author Eske Willerslev, an evolutionary geneticist with the University of Copenhagen in Denmark.

What Caused Deadly Plague?

Willerslev and other researchers looked for traces of plague-causing bacteria in remains from four cemeteries near Siberia's Lake Baikal. They found remnants of plague DNA in teeth from 18 ancient hunter-gatherers.

Dating the carbon in the bones revealed that the plague triggered two outbreaks, with the first cases detected around 5,500 years ago.

The team found that the prehistoric plague developed in stages and infected several small families. It likely spread from marmots — large native rodents — when people ate their raw organs or touched infected hides during butchery. The disease also traveled between people through coughing and sneezing, the authors said.

Kids were at Risk against Plague

Many of those who died were young children aged 8 to 11. Three young girls were buried side by side, two of whom were likely cousins. An aunt and nephew were found together, but her niece was in a different shared grave, according to the study published Wednesday in the journal Nature.

Kids may have been at greater risk because their immune systems weren’t as strong, researchers said.

The presence of multiple victims suggests that the prehistoric plague was capable of causing both individual cases and outbreaks, said geneticist Aida Andrades Valtueña with the Max Planck Institute for Evolutionary Anthropology. She had no role in the study.

Researchers found that this type of ancient plague evolved long before bubonic plague, which was responsible for the Black Death that struck medieval Europe. But there's evidence that earlier plagues were just as deadly. The disease decimated not only crowded cities, but also small, nomadic hunter-gatherer groups.

Knowing this can help us “understand the steps that the bacterium took to become the deadly pathogen we know today, and that can provide clues on how pathogens may emerge in the future,” Andrades Valtueña said in an email.